Viability of Infective Larvae of Haemonchus contortus, Ostertagia ostertagi, and Trichostrongylus colubriformis Following Exsheathment by Various Techniques

1996 ◽  
Vol 82 (1) ◽  
pp. 100 ◽  
Author(s):  
G. A. Conder ◽  
S. S. Johnson
Keyword(s):  
Haemonchus Contortus ◽  
Trichostrongylus Colubriformis ◽  
Ostertagia Ostertagi ◽  
Infective Larvae

Inhibited development in Haemonchus contortus

Parasitology ◽  
1975 ◽  
Vol 71 (2) ◽  
pp. 239-246 ◽  
Author(s):  
R. M. Connan
Keyword(s):  
Haemonchus Contortus ◽  
Primary Factor ◽  
High Rate ◽  
Environmental Stimulus ◽  
East Anglia ◽  
Ostertagia Ostertagi ◽  
Infective Larvae ◽  
Experimental Infections

Inhibited development of Haemonchus contortus was studied in single experimental infections of worm-free lambs. Chilling of the infective larvae at + 4°C was without effect on the percentage of larvae subsequently becoming inhibited and a period of exposure to autumnal conditions was unnecessary to induce a high rate of inhibition. It was concluded that seasonal inhibition of H. contortus in East Anglia is brought about primarily by an environmental stimulus acting upon the preparasitic stages but that, unlike Obeliscoides cuniculi and Ostertagia ostertagi, this was not cold. It could be provided in a culture kept in the dark at 25 °C for 12 days. While the age of the host did influence the phenomenon, in that larvae were less inclined to inhibition in very young animals, it was concluded that this was not a primary factor in the aetiology.

scholarly journals Epidemiologia das helmintoses gastrintestinais de ovinos no Planalto Catarinense

2004 ◽  
Vol 34 (6) ◽  
pp. 1889-1895 ◽  
Author(s):  
César Itaqui Ramos ◽  
Valdomiro Bellato ◽  
Antonio Pereira de Souza ◽  
Volney Silveira de Avila ◽  
Guilherme Caldeira Coutinho ◽  
...  
Keyword(s):  
Haemonchus Contortus ◽  
Santa Catarina ◽  
Trichostrongylus Colubriformis ◽  
Ostertagia Ostertagi ◽  
Cooperia Oncophora ◽  
Teladorsagia Circumcincta ◽  
Intestino Delgado

Este trabalho foi desenvolvido em três propriedades rurais nos municípios de Lages, São Joaquim e Campos Novos, estado de Santa Catarina, com os objetivos de determinar a prevalência, a intensidade e a variação sazonal de helmintos gastrintestinais e pulmonares em ovinos no Planalto Catarinense. Com base nos resultados aintenção é propor um esquema estratégico de controle. Para isso, foram utilizados mensalmente três cordeiros traçadores por propriedade, os quais, antes de serem conduzidos às mesmas, foram estabulados por 30 dias e executados tratamentos supressivos com anti-helmínticos de diferentes princípios ativos, com exames parasitológicos semanais para verificar a total eliminação de infecção parasitária. A seguir, foram encaminhados às três propriedades onde permaneceram em pastejo por 28 dias, sendo posteriormente recolhidos ao estábulo por mais 20 dias. Após foram sacrificados e realizada a coleta de alíquotas de 10% dos conteúdos do abomaso e intestino delgado, todos os helmintos do intestino grosso e pulmão. As maiores infecções por Haemonchus contortus ocorreram durante o período de outubro a março. O parasitismo por Trichostrongylus axei e Trichostrongylus colubriformis teve índices crescentes ao longo dos anos experimentais, apresentando maior pico de maio a outubro de 1999. Predominaram as espécies, no abomaso: Haemonchus contortus (100%); Trichostrongylus axei (98,7%); Trichostrongylus colubriformis (1,3%); Teladorsagia circumcincta (100%); Ostertagia ostertagi (100%). No intestino delgado: Trichostrongylus colubriformis (100%); Cooperia punctata (69,1%); Cooperia pectinata (18,4%); Cooperia curticei (6,9%); Cooperia oncophora (4,8%); Cooperia spatulata (0,8%) e Nematodirus spathiger (100%). No intestino grosso: Oesophagostomum venulosum (100%) e Trichuris ovis (100%). No pulmão, não foram encontrados parasitos.

scholarly journals Resistance of gastrointestinal nematodes to anthelmintics in sheep (Ovis aries)

2004 ◽  
Vol 47 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Vanete Thomaz-Soccol ◽  
Felipe Pohl de Souza ◽  
Cristina Sotomaior ◽  
Edilene Alcântara Castro ◽  
Viviane Milczewski ◽  
...  
Keyword(s):  
Haemonchus Contortus ◽  
Anthelmintic Resistance ◽  
Natural Infection ◽  
Gastrointestinal Nematodes ◽  
Ovis Aries ◽  
Multiple Resistance ◽  
Trichostrongylus Colubriformis ◽  
Infective Larvae ◽  
Reduction Test ◽  
Fecal Egg Count

The fecal egg count reduction test (FECRT) was used in a survey for anthelmintic resistance in 42 sheep farms, in five different regions in Paraná State, Brazil between July 1996 - July 2000. Animals with natural infection were tested. Five drugs were used individually or in combination - benzimidazole, imidazothiazole, ivermectin, milbemicina and closantel. Results showed that the prevalence of resistance to all anthelmintic was as high as 88.1% for benzimidazoles (oxfendazole), 78.6% for ivermectin, 56.4% for closantel, 38.7% for closantel + oxfendazole, 38% for levamisole, and 23.6% for moxidectin. There was multiple resistance in all tested farms. The most important infective larvae recovered from culture were Haemonchus contortus and Trichostrongylus colubriformis. The failure of the existing drugs in the State of Paraná is considered an important issue. Some proposals to improve the situation are suggested which include a change of attitude on anthelmintic use by sheepherders, veterinarians and sanitary authorities.

The differentiation of the infective larvae of some common nematode parasites of cattle

1953 ◽  
Vol 1 (2) ◽  
pp. 223 ◽  
Author(s):  
RK Keith
Keyword(s):  
Differential Diagnosis ◽  
Body Length ◽  
Haemonchus Contortus ◽  
Body Width ◽  
Ostertagia Ostertagi ◽  
Infective Larvae ◽  
Nematode Parasites ◽  
Cooperia Oncophora

Studies are reported on the differential diagnosis of the infective larvae of Strongyloides papillosus, Haemonchus contortus, Ostertagia ostertagi, Trichostrongylus axei, Cooperia oncophora, C. punctata, C. pectinata, Bunostornum phlebotomum, Nematodirus sp., and Oesophagostomum (Bosicola) radiatum, all of which occur in cattle in Queensland. These larvae can be readily identified by the length and shape of the tail, assisted by body length, body width, certain head and tail structures, and by the presence or absence of a sheath. A key for the identification of the larvae is given. Photographs of the larvae are also provided to assist identification.

Improved Methods of Obtaining Clean Larvae of Haemonchus contortus

1963 ◽  
Vol 37 (4) ◽  
pp. 251-254 ◽  
Author(s):  
M. G. Christie ◽  
J. E. Patterson
Keyword(s):  
Free Surface ◽  
Surface Area ◽  
Haemonchus Contortus ◽  
Water Repellent ◽  
Optimum Conditions ◽  
Infective Larvae ◽  
Mucous Coat ◽  
Third Stage ◽  
Free Surface Area ◽  
Improved Methods

A pellet of sheep faeces containing eggs of Haemonchus contortus forms an adequate environment for the development of those eggs to third stage infective larvae, provided that it is kept moist. Observation shows a concentration of developing larvae on the external mucous coat of the pellet. These data suggest that optimum conditions for development would occur when pellets are separated one from another and standing on a water repellent surface, thus presenting the maximum free surface area and minimum opportunity for aggregation and hence of over crowding. The best method of recovering the infective larvae would be one that obtained larvae free from contamination without requiring them to expend energy in separating themselves from the contamination.

Studies on resistance of sheep to infestation with Haemonchus contortus and Trichostrongylus spp. and on the immunological reactions of sheep exposed to infestation. I. The preparation of antigens for the complement fixation test and the reactivity of the biochemical fractions of H. contortus

1950 ◽  
Vol 1 (3) ◽  
pp. 285 ◽  
Author(s):  
DF Stewart
Keyword(s):  
Haemonchus Contortus ◽  
Complement Fixation Test ◽  
Complement Fixation ◽  
Fixation Test ◽  
Mature Adult ◽  
Infective Larvae ◽  
Lipid Fractions ◽  
Significant Difference ◽  
Third Stage ◽  
Free Material

All antigen was developed to detect circulating antibodies by means of the complement fixation test in sheep infested with Haemonchus contortus and Trichostrongylus spp. Extraction of worm material at 100°C. for 10 minutes was found to be the most satisfactory method for the preparation of antigens. Potent antigens were prepared from young adult H. contortus, from third-stage infective larvae, and from the eggs. Old mature adult H. contortus yielded antigens of low potency. No significant difference was found between the potency of antigens prepared from male and female adult H. contortus collected from the same sheep. Both adult Trichostrongylus spp. and third-stage infective larvae consistently yielded antigens of high potency. No significant difference was found in the results obtained with larval or adult H. contortus antigens, adjusted to the same potency and tested with natural H. contortus antisera. H. contortus and Trichostrongylus spp. absorbed the antiserum to each other. It was shown that a lipid was an essential constituent of the boiled antigen in the complement fixation reaction with natural antisera. Lipid-free antigens from H. contortus failed to react with natural antisera. The lipid was not antigenic when injected into rabbits. The carbohydrate fraction of H. contortus did not fix complement in the presence of natural antisera and was not antigenic when injected into rabbits. The lipid fraction of a variety of nematode parasites reacted with natural antisera to H. contortus infestation. Similar lipid fractions of two species of trematodes did not react with natural antisera to H. contortus infestation. Normal saline suspensions of the lipid-free material from a variety of helminths showed a greater degree of specificity when tested with artificially prepared antisera than did the lipid fractions.

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